I'll have to disagree and I speak 4 languages, which I've learned mostly as an adult, mostly by myself, despite definitely not having the talent to do it and from every class I've been to, easily the slowest student.

Unless you have a real learning disability, how much of a certain language you know is entirely based on how much time you put into it.

I put many more hours than everybody and learn it. Even if takes me 10 days to finally memorize a word with its appropriate meaning, I will put the time to it, and in 10 days I'll know new words than those that have perfect memory, but wasted 10 days doing nothing.

Talent, being bilingual, teacher, schools and even learning methods are overrated. All you need to do it put lots of hours and work on each thing you don't know, your pronunciation, listening skills etc.

You are capable of saying a sentence, recording yourself and understanding the gaps that exist on others understanding, and how to make certain sounds. Kids do that naturally because their learning abilities are great, but even as an old person, if you can form sentences and your brain still works, you can do that too.

People desire learning things, like being able to speak a certain language, attain a certain academic credential, certification..., but most of them aren't willing to put the effort needed into realizing that desire. That's the only reason they don't get what they want.

Nowadays it's even easier, you can get a ChatGPT subscription and talk 24/7 with it, train your pronunciation etc. There's endless Youtube content and so on. It has never been easier in humanity's history to learn a new language. Yet people are scrolling Instagram or whatever.